Magnetic space whirlpools give Mercury a plasma shower

To the list of scary things in space you can now add giant magnetic vortices. Huge swirls at the edge of Mercury's magnetosphere – where the planet's magnetic field meets the energetic charged particles of the solar wind – help shower the planet in solar plasma.

Kelvin-Helmholtz waves occur at the boundary between two fluids, such as two different bodies of air in Earth's atmosphere. They are most visible on Earth in the form of strange wave-like clouds.

KH waves also occur in the magnetospheres of some planets, and NASA's Messenger spacecraft found them around Mercury.

A new study of Messenger's data suggests the waves are stronger than thought – two to three times the strength of their terrestrial counterparts – and occur 10 to 30 times more frequently too.

Messenger also detected solar plasma in Mercury's magnetosphere linked to the KH waves, suggesting the large waves shuttle plasma towards the planet.

"KH waves are more important for mass and energy transfer than we imagined," says Torbjörn Sundberg at NASA's Goddard Space Flight Center in Greenbelt, Maryland.

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